This invention pertains to a unitized body submersible pump system for use in pumping molten metal.
Molten metal may be one of the more difficult environments in which to maintain a pump due to the heat and the corrosive factors within the molten metal. The submerged components of these pumps are typically made of graphite or similar materials due to the ability of these types of material compositions to withstand the heat and corrosive effects of the molten metal environment. While references may be made herein to molten aluminum, this is only used to give an example and not to limit the invention to aluminum pumps since the pump system disclosed herein may be used for pumping other molten metals.
Despite its positive properties for this application, graphite still corrodes and deteriorates over time and the pump must be maintained and replaced. The replacement or servicing of a pump operating submersed in molten metal is a time consuming exercise. First, the pump must first be removed from the molten metal, which causes down time of the metal furnace if that is the application. Then the pump along with the molten metal contained thereon must be allowed to sufficiently cool to allow it to be disassembled.
Once the deteriorated components are sufficiently cool, the molten metal built up on the various pump surfaces must be sufficiently removed to allow disassembly and/or re-use of the pump components. Then the pump must be re-assembled with the combination of old components or parts, along with the replacement parts. The downtime of a molten metal line may be as much as three to four days before it is operational again, which illustrates the importance of increasing the useful life of the pumps.
The useful life of a pump submersed varies greatly with the conditions of use, but it may be from twenty to sixty days for example.
The combination of the configuration and the number of components of typical prior art pumps make them difficult to efficiently and quickly assemble. A typical prior art pump is shown in FIG. 1, and includes a motor 2, a motor mount framework 3, a motor mount bracket 4, a rotating pump shaft 6 attached to an impeller housed in pump base 5, which is driven by the motor 2.
The prior art pump as shown in FIG. 1 further includes an output conduit which is formed in an output conduit body 7 (sometimes referred to as the riser tube), which is typically made of graphite and generally cylindrical with the internal conduit for the pumped molten metal to be pushed through by the impeller. The output conduit is placed through an aperture in the motor mount framework 3.
It is very important that motor 2, the shaft 6, the pump base 5 and the output conduit body 7 be accurately aligned in order for the pump system to work efficiently.
In the old or prior art way of providing a molten metal pump system, a special jig must be used to align the motor mount framework 3, the pump base 5, the pump shaft 6 and the output conduit body 7. The combination of the components is very heavy and because there are four components which must be accurately aligned and then secured to one another, substantial time must be taken to assemble the pump system in the precise manner required by the application. Hence the need for a jig to assemble the prior art pumps.
The four basic components of the prior art pump more or less form a parallelogram and it is important that it be a right angle type of parallelogram to enable the pump system, and especially the pump shaft 6 rotating the impeller in the pump base 5, to be accurately aligned.
It is therefore an object of this invention to provide a molten metal pump system which eliminates the need for using a separate jig to assemble or reassemble the pump components.
It is also an object of this invention to increase the useful life of the pump in the molten metal.
These objects and others are accomplished by this invention by the features more fully disclosed below, but including without limitation, the providing of an pump body which acts as the jig for the pump assemble, and which provides additional and differently configured graphite material around the output conduit, to increase the useful life of the pump.